Capacity Allocation Scheme of Hybrid Energy Storage System Based on Frequency Separation Control Optimization Strategy

In general, the hybrid energy storage system is an effective method to reduce the influence of impact load on the DC bus voltage stability. In hybrid energy storage systems (HESS), the frequency cut-off points of high and low frequency components will affect the capacity ratio, dynamic characteristics and economic benefits of lithium battery and supercapacitor. Therefore, this paper presents an energy management strategy (EMS) based on frequency division optimization control. First of all, based on the EMS to calculate each source needed to meet the energy response and power response. In addition, considering the differences in power density, energy density and price between the storage battery and the supercapacitor, an objective function aiming at the annual minimum input cost of the HESS is constructed. The optimal cutoff frequency of the HESS and its corresponding lowest cost capacity configuration are solved by iteration within the set cutoff frequency range. Finally, the test results show that when the cut-off frequency of lithium battery and supercapacitor is 0.0088Hz, the objective function takes the minimum value, which indicates the correctness and effectiveness of this test.